# see https://rosettacode.org/wiki/IPC_via_named_pipe#Raku
# Issues:
# - need to touch "in" before strings can be echoed into "in",
# - need to cat "out" before new strings can be echoed into "in"
# use mkfifo directly from libc
use NativeCall;
sub mkfifo(Str $pathname, int32 $mode --> int32) is native('libc.so.6') is symbol('mkfifo') {*}
# create filenames and named pipes in TMP
my ($in, $out) = <in out>.map: -> $name { $*TMPDIR.add("$name-$*PID") };
($in, $out).map: -> $name { mkfifo(Str($name), 0o666) };
('In :: Out', "$in :: $out")>>.say;
my atomicint $char-count = 0;
my Supply $in-changed = $in.dirname.IO.watch.grep({ .path eq $in and
.event ~~ FileChanged });
react { whenever $in-changed {
# calculate new char-count
given $in.open(:r) {
.lock: :shared;
say $char-count ⚛+= .readchars.chomp.codes;
.close;
}
# write new char-count to $out
given $out.open(:w) {
.lock;
.spurt: $char-count;
.close;
}
}
}
